Parameterization of state equations by quantum mechanics

The industrial chemistry of the 21st ^e century must meet a number of economic and environmental challenges in order to ensure its future development. Priority areas include process engineering (thermodynamics, kinetics, etc.) and modeling techniques (computational chemistry, process simulations, fluid dynamics, etc.).

While it is now generally accepted that quantum chemistry is one of the many facets of physical chemistry, the road to recognition of its ability to predict and interpret physical-chemical phenomena has not been a smooth one. Far from the unfounded diatribes of which it is still sometimes the target, computational chemistry is nonetheless busy winning its bet, as illustrated by this contribution from Gilbert Gaillard [1] , former chairman of the French company Hoechst: "Today, industrial chemistry has its source in theoretical chemistry, of which it is the application, the accomplishment, and which it contributes to enriching through the questions it submits to it. At the same time, it draws on the achievements of other fundamental sciences: physics, thermodynamics, mechanics, process engineering... These contributions make up its daily landscape and provide it with opportunities for development.

Quantum chemical methods involve the mathematical description of a system made up of nuclei and electrons, the building blocks of matter [2] , and the resolution of equations such as Schrödinger's equation. The practical application of these techniques involves the development and programming of algorithms for the quantitative description of physical and chemical phenomena within this system. The applications of computational chemistry in process engineering are many and varied: prediction of spectroscopic and thermochemical data, development of new molecules with selective reactivity, improvement of existing processes and design of new processes...

The example of equations of state is an excellent illustration of the ability of chemical engineers to apply and develop concepts and models originally conceived by theorists. This trend is becoming clearer with the advent and popularization of non-cubic equations of state [3] , which are gaining ground in industry.

Properties calculated at the quantum level can be used as a test variable for subsequent processing, thus contributing to a certain continuity between the different stages of physico-chemical property determination. This interface role is used extensively in this work. Thus, the parametrization of equations of...